Pigtailed neutrals on MWBC

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After reflecting upon the NEC definitions of Branch Circuit and MWBC, my opinion is that the definitions are consistent with both Al's interpretation and what I would consider the more common interpretation, that an MWBC is the portion of a branch circuit in which the "two or more ungrounded conductors" are actually present. Under this latter interpretation, the MWBC in the OP's example ends at the receptacle box, and so 300.13(B) permits continuity of the grounded conductor to the switch to depend on the device in the receptacle box.

Cheers, Wayne
 
al hildenbrand said:
So, a MWBC exists from the final OCPD to the Outlets . . . "to the Outlets", not to some arbitrary Outlet in the middle of other Outlets.
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While this interpretation is consistent with the definition, it is not the only possible interpretation. You are reading the definition of Branch Circuit as if it said (more clearly) "between the final OCPD and all outlets protected by that OCPD." Given the use of the wording "outlet(s)" it can also reasonably be read as "between the final OCPD and the outlet or outlets in question."

Under this latter reading, it is perfectly consistent that a pair of single pole breakers (with a handle tie) can protect on branch circuit on one leg, another branch circuit on the other leg, and a MWBC that includes only the circuit wiring where both ungrounded conductors are present.

Cheers, Wayne
 
jap said:
There was a graphic floating around somewhere that showed the neutral not needing to be pigtailed once it got pass the need of the 2 separate circuits.

Otherwise, if you talking about continuity, you could never use the back stabs for daisy chaining in any circumstance.

JAP>
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This what you want?

30013b001web2.gif
 
jumper said:
Is this what the OP has?

212ecmcbfig1.jpg
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No.
For some reason the installer pulled a 3 wire to the GD switch from the receptacle instead of a 2 wire.

The neutral in the switchbox may be capped off or it may possible be going off somewhere else with the red circuit.

The OP wasn't sure.

JAP>
 
al hildenbrand said:
And, in this situation, the neutral going on to the box containing the SWITCH of the OP is being shown as being required to be in the pigtail, NOT relying on the device for the splice.
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You had said earlier that you considered the entire circuit as a MWBC meaning that the continuity thing applied to the "whole circuit" as far as not relying on the device for the continuity of the grounded conductor, and that we couldn't pick and choose what outlets that applied to.

If you stand by that statement, then the middle receptacle on the red circuit in the graphic could not be daisy chained as pictured in the graphic.

It would have to be pigtailed also.


JAP>
 
jap said:
No.
For some reason the installer pulled a 3 wire to the GD switch from the receptacle instead of a 2 wire.

The neutral in the switchbox may be capped off or it may possible be going off somewhere else with the red circuit.

The OP wasn't sure.

JAP>
Click to expand...

There lays the problem. We are required to have a neutral at the switch location.
Doesn't matter if it is used or not as far as the NEC is concerned.
​
I have to admit that the installer did this correctly although I sure wouldn't have thought of it for a GD switch. He just didn't pigtail the neutral at the device where the MWBC is utilized for line to neutral loads.

Add: He didn't have handle ties at the CBs either
 
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wwhitney said:
Sure it does, it only shows pigtailing required where the neutral serves downstream loads on both legs. The neutral to the OP's receptacle doesn't.

Cheers, Wayne
Click to expand...

Correction,
The neutral from the panel to the OP"s dual fed receptacle does serve the load on both legs, but, the wire under the neutral screw of the receptacle to the switch does not.


JAP>
 
jap said:
Correction,
The neutral from the panel to the OP"s dual fed receptacle does serve the load on both legs, but, the wire under the neutral screw of the receptacle to the switch does not
Click to expand...

And, when we get to the end of the neutral conductor from the panel to the dual fed receptacle, you are claiming that the single hot's neutral of each "1 circuit" need only be spliced by the duplex receptacle terminals, which is different than what Mike Holt's diagram says is required by 300.13(B).
 
jap said:
The neutral from the panel to the OP"s dual fed receptacle does serve the load on both legs, but, the wire under the neutral screw of the receptacle to the switch does not.
Click to expand...
I think we are in agreement, the neutral wire feeding downstream of the receptacle serves loads on only leg, so the receptacle doesn't require pigtailing. Which is what I said.

Cheers, Wayne
 
So reading 300.13(B) a little more closely, I see that the wording is ambiguous. You could read it as referring to ((continuity within the MWBC) of the grounded conductor) or as (continuity of the grounded conductor) within the MWBC). In the former reading, the receptacle doesn't need pigtailing, as it is at the end of the MWBC, at least for the usual reading of the definition of MWBC, so if you interrupt the grounded conductor there, the grounded conductor is still continuous within the MWBC. Under the latter reading, which I hadn't previously considered, the device needs pigtailing.

Cheers, Wayne
 
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